Wind Farm Converter Voltage Ramping Under Black Start Limits
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Solution Overview
Problem
Conventional methods for black starting a wind park rely on stable voltage and frequency, which are not feasible for wind farms using power converters, and the reliability of thermal power stations is expected to decline, necessitating the ability for wind farms to perform self-black starting.
Innovation Solution
A method for controlling utility grid side converters of wind turbines to ramp up voltage during black start, assessing and respecting limits on active power, frequency, and current, allowing autonomous operation and energization of the wind park grid without external utility grid power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wind turbines use power converters to interface with the grid, then power conversion and control capability are improved, but the ability to perform black start is lost because converters require stable voltage and frequency to operate
Solution Approach 1:
The wind farm performs self-black-starting using its own wind resources and power converters without external assistance. The control system autonomously manages the black start process by ramping up voltage, assessing power conditions, and coordinating converter operation to energize the grid independently, eliminating dependence on thermal power stations or external grid support.
Solution Approach 2:
The power converters operate in an unconventional manner by dynamically changing voltage parameters during black start. Instead of requiring stable grid voltage and frequency, the converters actively ramp up voltage from zero to nominal levels, assess active power conditions, and adjust operating parameters to establish stable grid-forming operation, thereby enabling black start capability despite being designed for grid-following operation.
2Reliability
If conventional thermal power stations are used for black start, then reliable black start capability is achieved, but the solution becomes obsolete as thermal power station availability and reliability are expected to decline
Solution Approach 1:
The wind farm performs self-black-starting using its own wind resources and power converters without external assistance. The control system autonomously manages the black start process by ramping up voltage, assessing power conditions, and coordinating converter operation to energize the grid independently, eliminating dependence on thermal power stations or external grid support.
Solution Approach 2:
The power converters are designed to perform multiple functions: normal grid-connected operation and black start capability. By implementing grid-forming control algorithms and voltage ramping functionality, the converters can operate in both grid-following and grid-forming modes, making the wind farm versatile and adaptable to different operational scenarios including future scenarios where thermal power stations are unavailable.
3Productivity
If voltage is ramped up quickly during black start, then black start speed is improved, but converter damage may occur due to exceeding active power, frequency, or current limits
Solution Approach 1:
The control system continuously monitors voltage, active power, frequency, and current parameters during the black start process. Based on feedback from these measurements, the system dynamically adjusts the voltage ramping rate and converter operation to prevent exceeding safety limits while maintaining fast black start performance. The loop continuously assesses conditions and modifies control actions accordingly.
Solution Approach 2:
The voltage ramping process is dynamic rather than static. The ramping rate is continuously adjusted based on real-time assessment of active power availability, frequency conditions, and current limits. The system transitions from aggressive voltage increase when conditions permit to controlled ramping or freezing when limits are approached, optimizing both speed and safety throughout the black start process.
Data Source
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AI summary
It is described a method of controlling at least one converter of at least one wind turbine connectable to a wind park grid of a wind park during black start or island mode of the wind park, the method comprising: ramping up (9) a converter voltage reference (Vref, 105, 77) unless a power related condition and/or a wind park grid frequency related condition or a converter current related condition is violated.